1. Field of the Invention
The present invention relates to a steering device that includes a tilt and telescopic adjustment mechanism and that is capable of preventing a buffer member that absorbs impact from making contact with a metal member that forms a fastener performing locking and unlocking during the tilt and telescopic adjustment for a long period to be pressure-welded to the metal member to cause a problem in the tilt and telescopic adjustment operation.
2. Description of the Related Art
The present applicant has developed various structures of a steering device having a tilt and telescopic adjustment mechanism, for absorbing impact caused by contacting between members during the tilt and telescopic adjustment to reduce impact and impact sound. As an example, Japanese Patent Application Publication No. 2011-168265 discloses a steering device. Members associated with the tilt and telescopic adjustment mechanism include a fastener that includes a bolt shaft and the like, a buffer member for reducing impact, and other members.
In the steering device disclosed in Japanese Patent Application Publication No. 2011-168265, two buffer members 5 formed of elastic rubber are mounted on a slide guide 4, and the slide guide 4 is mounted so as to surround a bolt shaft 71 of a fastener 7. On the other hand, a stopper bracket 3 includes a movable guide portion 31 and stopper plates 32 formed at both ends in a front-rear direction of the movable guide portion 31. The stopper bracket 3 is attached to a lower end position in a radial direction of a column pipe 1 and moves in the front-rear direction in relation to an outer housing 2 together with the column pipe 1 during telescopic adjustment.
During telescopic adjustment, the column pipe 1 moves in an axial direction in relation to the outer housing 2. In this case, any one of both stopper plates 32 of the stopper bracket 3 fixed to the column pipe 1 makes contact with the buffer member 5 to perform a role of a stopper that restricts a telescopic adjustment range.
In the steering device disclosed in Japanese Patent Application Publication No. 2011-168265, even when the column pipe 1 is expanded or contracted in its maximum or minimum limit, the buffer member 5 makes contact with the stopper plate 32 of the stopper bracket 3. Moreover, a contacting surface of the buffer member 5 making contact with the stopper plate 32 is configured as a concave circular arc-shaped surface. When the buffer member 5 and the stopper plate 32 make contact with each other, the contact starts with point-contact or a line-contact and gradually changes to surface-contact.
Due to this, even when the buffer member 5 and the stopper plate 32 collide strongly with each other until the contact becomes approximately surface-contact, the contacting is completed while the buffer member 5 absorbs impact, and the durability of the buffer member 5 can be secured sufficiently.
The telescopic adjustment range is formed with a certain degree of margin, and it is not common for a steering wheel to be used in the limit range of telescopic adjustment. However, for drivers, there may be often a case where any one of the positions at which the column pipe 1 is expanded or contracted in its maximum and minimum limit is the optimum position of the steering wheel. In this case, an automobile is driven in a state where the buffer member 5 is in contact with the stopper plate 32.
Even when the contacting surface of the buffer member 5 is configured as a concave circular arc-shaped surface, if the contact state continues for a long period, the circular arc-shaped surface is gradually deformed into a flat surface, and the buffer member 5 and the stopper plate 32 make surface-contact. Moreover, due to a long period of the surface-contact, the buffer member 5 and the stopper plate 32 are pressure-welded.